Preparation of Alkyl Halides

Following are two methods commonly used to prepare alkyl halides.
Hydrogen halide addition to an alkene
Halogen halides add across carbon-carbon double bonds. These additions follow Markovnikov's rule, which states that the positive part of a reagent (a hydrogen atom, for example) adds to the carbon of the double bond that already has more hydrogen atoms attached to it. The negative part adds to the other carbon of the double bond. Such an arrangement leads to the formation of the more stable carbocation over other less-stable intermediates.

Reaction of alcohols with sulfur and phosphorous halides
Alcohols can be converted to alkyl halides by reaction with thionyl chloride, SOCl2•, phosphorous trichloride, PCl3•, phosphorous pentachloride, PCl5•, or phosphorous tribromide, PBr3. For example, ethyl chloride or ethyl bromide can be prepared from ethyl alcohol via reactions with sulfur and phosphorous halides. 

Grignard Reaction

In a Grignard reaction, an alkyl halide reacts with magnesium metal in an anhydrous ether solvent to create an organometallic reagent. 

The Grignard reagent is highly reactive and is used to prepare many functional groups. An example is the preparation of a carboxylic acid by reaction with carbon dioxide and mineral acid.

E2 mechanism

Elimination reactions can also occur when a carbon halogen bond does not completely ionize, but merely becomes polarized. As with the E1 reactions, E2 mechanisms occur when the attacking group displays its basic characteristics rather than its nucleophilic property. The activated complex for this mechanism contains both the alkyl halide and the alkoxide ion.
Following is the complete mechanism for the E2 elimination reaction:

Mechanism of Elimination Reactions

As noted earlier, the halogen-carbon bond in an alkyl halide is polarized due to the electronegativity difference between the atoms. This polarization can lead to the formation of a partial or fully positive charge on the carbon atom

The full or partial positive charge on the carbon atom is delocalized (dispersed) down the carbon chain. This, in turn, makes the hydrogen atoms attached to these carbons very slightly positive and thus very weakly acidic. Therefore, a very strong base can now remove slightly positive hydrogen with the resulting release of electrons down the chain, forming a π bond between the carbon atoms. The actual mechanism can be one of two types, E1 or E2, depending upon the structure of the activated complex.
E1 mechanism
An atom that bears a pair of unshared electrons takes on one of two roles. The atom may share these electrons with a carbon atom that bears a leaving group, or it may share these electrons with a hydrogen atom. In the former case, the atom acts as a nucleophile, while in the latter case it acts as a base. Therefore, depending on reaction conditions, the atom may be involved in a substitution reaction or an elimination reaction.
The reaction of an OH− ion with tertiary butyl bromide leads to little or no substitution product because steric hindrance blocks the rear lobe of the carbon atom to which the bromine atom is bonded. With the aid of a polar solvent, the bromine-carbon bond ionizes to form a tertiary carbocation and a bromide ion. The hydrogen atoms on the carbons adjacent to the carbocation carbon acquire a slight positive charge, allowing the OH− ion to employ its basic characteristics. Thus, the OH− ion abstracts a hydrogen atom, and the electrons migrate down the chain, forming a double bond. 

The activated complex for this reaction contains only the alkyl halide and is, therefore, unimolecular. The reaction follows an E1 mechanism

Elimination Reactions

During an elimination reaction, a bond forms by the removal of two atoms or groups from the original molecule. In most instances, the bond that forms is a π bond. Elimination reactions compete with substitution reactions when alkyl halides react with a nucleophile. 

The elimination of hydrogen halide (a halogen acid) from an alkyl halide requires a strong base such as the alkoxide ion, RO−. Weaker bases such as the OH− ion give poor yields of elimination product. 
If an alkyl halide contains more than two carbons in its chain, and the carbon atoms adjacent to the carbon atom bonded to the halogen each have hydrogen atoms bonded to them, two products will form. The major product is predicted by Zaitsev's Rule, which states that the more highly branched alkene will be the major product. For example, in the dehydrohalogenation reaction between 2-chlorobutane and sodium methoxide, the major product is 2-butene. 

SN1 mechanism

The second major type of nucleophilic substitution mechanism is the SN1 mechanism. This mechanism proceeds via two steps. The first step (the slow step) involves the breakdown of the alkyl halide into an alkyl carbocation and a leaving group anion. The second step (the fast step) involves the formation of a bond between the nucleophile and the alkyl carbocation

Because the activated complex contains only one species—the alkyl carbocation—the substitution is considered unimolecular.
Carbocations contain sp2 hybridized orbitals and thus have planar structures. SN1 mechanisms proceed via a carbocation intermediate, so a nucleophile attack is equally possible from either side of the plane. Therefore, a pure, optically active alkyl halide undergoing an SN1 substitution reaction will generate a racemic mixture as a product, as shown in Figure . 

Solvent effects

For protic solvents (solvents capable of forming hydrogen bonds in solution), an increase in the solvent's polarity results in a decrease in the rate of SN2 reactions. This decrease occurs because protic solvents solvate the nucleophile, thus lowering its ground state energy. Because the energy of the activated complex is a fixed value, the energy of activation becomes greater and, therefore, the rate of reaction decreases. 
Polar aprotic solvents (solvents that cannot form hydrogen bonds in solution) do not solvate the nucleophile but rather surround the accompanying cation, thereby raising the ground state energy of the nucleophile. Because the energy of the activated complex is a fixed value, the energy of activation becomes less and, therefore, the rate of reaction increases. 

Figure illustrates the effect of solvent polarity on the energy of activation and, thus, the rate of reaction

The smaller activation energy leads to the more rapid reaction.

Steric hindrance

SN2 reactions require a rearward attack on the carbon bonded to the leaving group. If a large number of groups are bonded to the same carbon that bears the leaving group, the nucleophile's attack should be hindered and the rate of the reaction slowed. This phenomenon is called steric hindrance. The larger and bulkier the group(s), the greater the steric hindrance and the slower the rate of reaction. Table shows the effect of steric hindrance on the rate of reaction for a specific, unspecified nucleophile and leaving group. Different nucleophiles and leaving groups would result in different numbers but similar patterns of results. 
TABLE 1 Effects of Steric Hindrance upon Rates of SN2 Reactions 
 

Alkyl Group (ALK) Relative Rate of Substitution 
−CH3(small group) 30
−CH2CH3 (larger group) 1
−CH(CH3)2 (bulky group) 0.03
−C(CH3)3 (very bulky group) 0

SN2 reactions give good yields on 1° (primary) alkyl halides, moderate yields on 2° (secondary) alkyl halides, and poor to no yields on 3° (tertiary) alkyl halides. 

Nucleophilic Substitution Reactions: Mechanisms

SN2 Mechanism 
Experimental data from nucleophilic substitution reactions on substrates that have optical activity (the ability to rotate plane-polarized light) shows that two general mechanisms exist for these types of reactions. The first type is called an SN2 mechanism. This mechanism follows second-order kinetics (the reaction rate depends on the concentrations of two reactants), and its intermediate contains both the substrate and the nucleophile and is therefore bimolecular. The terminology SN2 stands for “substitution nucleophilic bimolecular.” 
The second type of mechanism is an SN1 mechanism. This mechanism follows first-order kinetics (the reaction rate depends on the concentration of one reactant), and its intermediate contains only the substrate molecule and is therefore unimolecular. The terminology SN1 stands for “substitution nucleophilic unimolecular.” 
SN2 mechanism 
The alkyl halide substrate contains a polarized carbon halogen bond. The SN2 mechanism begins when an electron pair of the nucleophile attacks the back lobe of the leaving group. Carbon in the resulting complex is trigonal bipyramidal in shape. With the loss of the leaving group, the carbon atom again assumes a pyramidal shape; however, its configuration is inverted. See Figure below. 

The SN2 mechanism can also be illustrated as shown in Figure . 

Notice that in either picture, the intermediate shows both the nucleophile and the substrate. Also notice that the nucleophile must always attack from the side opposite the side that contains the leaving group. This occurs because the nucleophilic attack is always on the back lobe (antibonding orbital) of the carbon atom acting as the nucleus.
SN2 mechanisms always proceed via rearward attack of the nucleophile on the substrate. This process results in the inversion of the relative configuration, going from starting material to product. This inversion is often called the Walden inversion, and this mechanism is sometimes illustrated as shown in Figure . 

Nucleophilic Substitution Reactions

Alkyl halides undergo many reactions in which a nucleophile displaces the halogen atom bonded to the central carbon of the molecule. The displaced halogen atom becomes a halide ion.

Some typical nucleophiles are the hydroxy group (−OH), the alkoxy group (RO−), and the cyanide ion (−C N). Reaction of these nucleophiles with an alkyl halide (R—X) gives the following reactions and products: 

The halogen ion that is displaced from the carbon atom is called the leaving group, and the overall reaction is called a nucleophilic substitution reaction

Nucleus and Nucleophiles

A nucleus is any atom that has a partial or fully positive charge associated with it. A nucleophile is an atom or group that is attracted to a source of partial or full positive charge. Alkyl halides act as a nucleus because of the great electronegativity differences between the carbon atom and the halogen atom directly bonded to it. This great electronegativity difference causes the electron density in the overlap region between the carbon and halogen atoms to be pulled toward the halogen atom. This shifting of electron density in the molecule makes the carbon atom partially positive (the nucleus) and the halide ion partially negative (the incipient leaving group). 
Figure illustrates the effect of electronegativity differences on bond polarity. 

Electrons in the overlap region between the carbon and the halogen atoms are attracted to the more electronegative halogen atom. The carbon atom, which now has less of a share of the bonding electrons, becomes partially positive, and the halogen atom, which has a greater share of these electrons, becomes partially negative.
Remember that a nucleophile is a substance that has a pair of electrons that it can donate to another atom. The weaker the forces of attraction holding the electron pair to the original molecule, the more readily this molecule will share the electrons and the stronger the resulting nucleophile will be. The weakest held electrons on an atom are the nonbonding electron pairs. Electrons in π bonds, although held more strongly than nonbonding electrons, are also loosely held and easily shared, making unsaturated compounds relatively good Nucleophiles.
Because they possess a negative charge, anions are always better Nucleophiles than their conjugate acids.

Physical properties

Alkyl halides have little solubility in water but good solubility with nonpolar solvents, such as hexane. Many of the low molecular weight alkyl halides are used as solvents in reactions that involve nonpolar reactants, such as bromine. The boiling points of different alkyl halides containing the same halogen increase with increasing chain length. For a given chain length, the boiling point increases as the halogen is changed from fluorine to iodine. For isomers of the same compound, the compound with the more highly-branched alkyl group normally has the lowest boiling point. Table summarizes data for some representative alkyl halides. 
TABLE 1 Boiling Points (°C) of Alkyl Halides 
                         Flouride Chloride Bromide Iodine 
Group                   bp         bp              bp        bp 
Methyl             −78.4     −28.8        −3.6     42.5
Ethyl                −37.7       13.1         38.4       72
Propyl            −2.5        46.6           70.8     102
Isopropyl       −9.4      34             59.4        89.4
Butyl                32      78.4             101          130
Sec-butyl                     68              91.2         120
Tert−butyl                       51           73.3       100

Introduction to Alkyl Halides

An alkyl halide is another name for a halogen-substituted alkane. The carbon atom, which is bonded to the halogen atom, has sp3 hybridized bonding orbitals and exhibits a tetrahedral shape. Due to electronegativity differences between the carbon and halogen atoms, the σ covalent bond between these atoms is polarized, with the carbon atom becoming slightly positive and the halogen atom partially negative. Halogen atoms increase in size and decrease in electronegativity going down the family in the periodic table. Therefore, the bond length between carbon and halogen becomes longer and less polar as the halogen atom changes from fluorine to iodine. 

Alkene

Alkene

An alkene is one of the three classes of unsaturated hydrocarbons that contain at least one carbon-carbon double bond and have the general molecular formula of CnH2n (the other two being alkynes and arenes).

The simplest alkene is C2H4, which has the common name "ethylene" and theIUPAC name "ethene".

Structure of Alkenes
Shape of Alkenes
As predicted by the VSEPR model of electron pair replusion (see covalent bond), the bond angles about each carbon in a double bond are about 120°, although the angle may be larger because of strain introduced by nonbonded interactions created by groups attached to the carbons of the double bond. For example, the C-C-C bond angle in propene (propylene) is 123.9°.
Molecular Geometry Carbon-Carbon Double Bond
Like single covalent bonds, double bonds can be described in terms of overlapping atomic orbitals, except that unlike a single bond (which consist of a single sigma bond), a carbon-carbon double bond consists of one sigma bond and one pi bond.
Each carbon of the double bond uses its three sp2 hybrid orbitals to form sigma bonds to three atoms. The unhybridized 2p atomic orbitals, which lie perpendicular to the plane created by the axes of the three sp2 hybrid orbitals, combine to form the pi bond.
Because it requires a large amount of energy to break a pi bond (264 kJ/mol in ethylene), rotation about the carbon-carbon double bond is very difficult and therefore severely restricted.
Reactions
Synthesis
1. The most common industrial synthesis path for alkenes is cracking of petroleum.
2. Alkenes can be synthesized from alcohols via an elimination reaction that removes one water molecule:
H3C-CH2-OH + H2SO4 → H3C-CH2-O-SO3H + H2O → H2C=CH2 + H2SO4
3. Catalytic synthesis of higher α-alkenes can be achieved by a reaction of ethene with triethylaluminium, an organometallic compound in the presence of nickel, cobalt or platinum.
Addition reactions
Catalytic addition of hydrogen
Catalytic hydrogenation of alkenes produce the corresponding alkanes. The reaction is carried out under pressure in the presence of a metallic catalyst. Common industrial catalysts are based on platinum, nickelor palladium, for laboratory syntheses, Raney's nickel is often employed. This is an alloy of nickel and aluminium.
This is the catalytic hydrogenation of ethylene to yield ethane:
CH2=CH2 + H2 → CH3-CH3
Electrophilic addition
Most addition reactions to alkenes follow the mechanism of electrophilic addition.
1. Halogenation: Addition of elementary bromine or chlorine to alkenes yield vicinal Dibromo- and dichloroalkenes, respectively. The decoloration of a solution of bromine in water is an analytical test for the presence of alkenes:
CH2=CH2 + Br2 → BrCH2-CH2Br
2. Hydrohalogenation: Addition of hydrohalic acids like HCl or HBr to alkenes yield the corresponding haloalkanes.
CH3-CH=CH2 + HBr → CH3-CHBr-CH3
If the two carbon atoms at the double bond are linked to a different number of hydrogen atoms, the halogen is found preferentially at the carbon with less hydrogen substituents (Markovnikov's rule).
3. Addition of a carbene or carbenoid yields the corresponding cyclopropane
Oxidation
1. In the presence of oxygen, alkenes burn with a bright flame to carbon dioxide and water.
2. Catalytic oxidation with oxygen or the reaction with percarboxylic acids yields epoxides
3. Reaction with ozone leads to the breaking of the double bond, yielding two aldehydes or ketones
R1-CH=CH-R2 + O3 → R1-CHO + R2-CHO + H2O
This reaction can be used to determine the position of a double bond in an unknown alkene.
Polymerisation
Polymerization of alkenes is an economically important reaction which yields polymers of high industrial value, such as the plastics polyethylene and polypropylene. Polymerization can either proceed via a free-radical or an ionic mechanism. For detail regarding the reaction mechanisms, see the polymerization article.

Nomenclature of Alkenes
IUPAC Names
To form the root of the IUPAC names for alkenes, simply change the -an- infix of the parent to -en-. For example, CH3-CH3 is the alkane ethANe. The name of CH2=CH2 is therefore ethENe.
In higher alkenes, where isomers exist that differ in location of the double bond, the following numbering system is used:
1. Number the longest carbon chain the contains the double bond in the direction that gives the carbon atoms of the double bond the lowest possible numbers.
2. Indicate the location of the double bond by the location of its first carbon
3. Name branched or substituted alkenes in a manner similar to alkanes.
4. Number the carbon atoms, locate and name substituent groups, locate the double bond, and name the main chain
CH3CH2CH2CH2CH==CH26 5 4 3 2 1
1-Hexene CH3 |CH3CH2CH2CH2CH==CH26 5 4 3 2 1
4-Methyl-1-hexene CH3 | CH3CH2CH2CH2CH==CH26 5 4 3 |2 1 CH2CH3
2-Ethyl-4-methyl-1-hexene
Common Names
Despite the precision and universal acceptance of the IUPAC naming system, some alkenes are known almost exclusively by their common names:
 CH2="CH2" CH3CH="CH2" CH3C(CH3)="CH2"
IUPAC name: Ethene Propene 2-Methylpropene
Common name: Ethylene Propylene Isobutylene

Cycloalkane

Cycloalkane
Cycloalkanes are chemical compounds with a single ring of carbons to which hydrogens are attached according to the formula CnH2n. They are named analogously to their normal alkane counterpart of the same carbon count: cyclopropane, cyclobutane, cyclopentane, cyclohexane, etc.

Cycloalkanes are classified into small, normal and bigger cycloalkanes, where cyclopropane and cyclobutane are the small ones, cyclopentane, cyclohexane, cycloheptane are the normal ones, and the rest are the bigger ones.

Nomenclature
he naming of polycyclic alkanes is more complex, with the base name indicating the number of carbons in the ring system, a prefix indicating the number of rings (eg, "bicyclo"), and a numeric prefix before that indicating the number of carbons in each part of each ring, exclusive of vertices. For instance, a bicyclooctane which consists of a six-member ring and a four member ring, which share two adjacent carbon atoms which form a shared edge, is [4.2.0]-bicyclooctane. That part of the six-member ring, exclusive of the shared edge has 4 carbons. That part of the four-member ring, exclusive of the shared edge, has 2 carbons. The edge itself, exclusive of the two vertices that define it, has 0 carbons.
Reactions
The normal and the bigger cycloalkanes are very stable, like alkanes, and their reactions (cf. radicalic chain reactions ) are like alkanes.
The small cycloalkanes - particularly cyclopropane - have a lower stability due to the Baeyer-tension . They react similar to alkenes, though they don't react with the EA (cf. electrophilic addition), but with the SN2 (cf. nucleophilic substitution) reaction mechanism. These reactions are ring opening reactions or cleavage reactions of alkyl cycloalkanes.

Reactions of alkane

Cracking reactions
"Cracking" breaks larger molecules into smaller ones. This can be done with a thermic or catalytic method. The thermal cracking process follows a homolytic mechanism, that is, bonds break symmetrically and thus pairs of free radicals are formed. The catalytic cracking process involves the presence of acid catalysts (usually solid acids such as silica-alumina and zeolites) which promote a heterolytic (asymmetric) breakage of bonds yielding pairs of ions of opposite charges, usually a carbocation and the very unstable hydride anion. Carbon-localized free radicals and cations are both highly unstable and undergo processes of chain rearrangement, C-C scission in position beta (i.e., cracking) and intra-and intermolecular hydrogen transfer or hydride transfer . In both types of processes, the corresponding reactive intermediates (radicals, ions) are permanently regenerated, and thus they proceed by a self-propagating chain mechanism. The chain of reactions is eventually terminated by radical or ion recombination.
Here is an example of cracking with butane CH3-CH2-CH2-CH3
• 1st possibility (48%): breaking is done on the CH3-CH2 bond.
CH3* / *CH2-CH2-CH3
after a certain number of steps, we will obtain an alkane and an alkene: CH4 + CH2=CH-CH3
• 2nd possibility (38%): breaking is done on the CH2-CH2 bond.
CH3-CH2* / *CH2-CH3
after a certain number of steps, we will obtain an alkane and an alkene from different types: CH3-CH3 + CH2=CH2
• 3rd possibility (14%): breaking of a C-H bond
after a certain number of steps, we will obtain an alkene and hydrogen gas: CH2=CH-CH2-CH3 + H2
Halogenation reaction
R + X2 → RX + HX
These are the steps when methane is chlorinated. This a highly exothermic reaction that can lead to an explosion.
1. Initiation step: splitting of a chlorine molecule to form two chlorine atoms. A chlorine atom has an unpaired electron and acts as a free radical.
Cl2 → Cl* / *Cl
energy provided by UV.
2. Propagation (two steps): a hydrogen atom is pulled off from methane then the methyl pulls a Cl from Cl2
CH4 + Cl* → CH3* + HCl
CH3* + Cl2 → CH3Cl + Cl*
This results in the desired product plus another Chlorine radical. This radical will then go on to take part in another propagation reaction causing a chain reaction. If there is an excess of Chlorine, other products like CH2Cl2 may be formed.
3. Termination step: recombination of two free radicals
• Cl* + Cl* → Cl2, or
• CH3* + Cl* → CH3Cl, or
• CH3* + CH3* → C2H6.
The last possibilty in the termination step will result in an impurity in the final mixture; notably this results in an organic molecule with a longer carbon chain than the reactants.
Combustion
R + O2 → CO2 + H2O + H2
Is a very exothermic reaction. If the quantity of O2 is insufficient, it will form a poison called carbon monoxide (CO). Here is an example with methane:
CH4 + 2 O2 → CO2 + 2 H2O
with less O2:
2 CH4 + 3 O2 → 2 CO + 4 H2O
with even less O2:
CH4 + O2 → C + 2 H2O

Alkane

Alkane
An alkane in organic chemistry is a type of hydrocarbon in which the molecule has the maximum possible number of hydrogen atoms and so has no double bonds (they are saturated).
The general formula for acyclic/linear alkanes, also known as aliphatic hydrocarbons is CnH2n+2; the simplest possible alkane is methane (CH4). The next in the series is ethane (C2H6) and the series continues with larger and larger molecules. Each C atom is hybridized sp3. The series of alkanes is often 
Properties
Arrangements
The atoms in alkanes with more than three carbon atoms can be arranged in multiple ways, forming different isomers. "Normal" alkanes have the most linear, unbranched configuration, and are denoted with an n. The number of isomers increases rapidly with the number of carbon atoms; for acyclic alkanes with n = 1..12 carbon atoms, the number of isomers equals 1, 1, 1, 2, 3, 5, 9, 18, 35, 75, 159, 355 .
The names of all alkanes end with -ane. The alkanes, and their derivatives, with four or fewer carbons have non-systematic common names, established by long precedence. For a more complete list, see List of alkanes.
methane CH4
ethane C2H6
propane C3H8
n-butane C4H10
n-pentane C5H12
n-hexane C6H14
n-heptane C7H16
n-octane C8H18

Branched alkanes have some non-systematic (or "trivial") names in common use, but there is also a systematic way of naming most such compounds, which starts from identifying the longest non-branched parent alkane in the molecule, counting up from one sequentially starting from the carbon involved in the most prominent functional group (or, more formally, attached to the collection of heteroatoms with highest priority according to some rules), and then numbering the side chains according to this sequen

is the only other C4 alkane isomer possible, aside from n-butane. Its formal name is 2-methylpropane.
Pentane, however, has two branched isomers, in addition to its strictly linear, normal form:

Naming Alkanes
Alkanes are named according to IUPAC nomenclature. The suffix of an alkanes name is always -ane. The prefix depends on the number of carbon atoms in the molecule and on any branched chains that may be attached. Refer to IUPAC nomenclature for greater detail

Hydrocarbon

Hydrocarbon
In chemistry, a hydrocarbon is a group of chemical compounds consisting only of carbon (C) and hydrogen (H). They all consist of a carbon backbone and atoms of hydrogen attached to that backbone. (Often the term is used as a shortened form of the term aliphatic hydrocarbon.)
For example, methane (swamp gas/marsh gas) is a hydrocarbon with one carbon atom and four hydrogen atoms: CH4. Ethane is a hydrocarbon (more specifically, an alkane) consisting of two carbon atoms held together with a single bond, each with three hydrogen atoms bonded: C2H6. Propane has three C atoms (C3H8) and so on (CnH2•n+2).
There are basically three types of hydrocarbons:
1. aromatic hydrocarbons, which have at least one aromatic ring in addition to whatever bonds they have
2. saturated hydrocarbons, also known as alkanes, which don't have double, triple or aromatic bonds
3. unsaturated hydrocarbons, which have one or more double or triple bonds between carbon atoms, are divided into:
• alkenes
• alkynes
• dienes
The number of hydrogen atoms in hydrocarbons can be determined, if the number of carbon atoms is known, by using these following equations:
• Alkanes: CnH2n+2
• Alkenes: CnH2n (assuming only one double bond)
• Alkenes: CnH2n-2 (assuming only one triple bond)

Liquid geologically-extracted hydrocarbons are referred to as petroleum (literally "rock oil") or mineral oil, while gaseous geologic hydrocarbons are referred to as natural gas. All are significant sources of fuel and raw materials as a feedstock for the production of organic chemicals and are commonly found in the subsurface using the tools of petroleum geology.
Hydrocarbons are of prime economic importance because they encompass the constituents of the major fossil fuels (coal,petroleum, natural gas, etc.) and biofuels, as well as plastics, waxes, solvents and oils. In urban pollution, these components--along with NOx and sunlight--all contribute to the formation of tropospheri ozone.

Nomenclature of Organic compound

Nomenclature of Organic compound
Organic nomenclature is the system established for naming and grouping organic compounds.
Formally, rules established by the International Union of Pure and Applied Chemistry (known as IUPAC nomenclature) are authoritative for the names of organic compounds, but in practice, a number of simply-applied rules can allow one to use and understand the names of many organic compounds.
For many compounds, naming can begin by determining the name of the parent hydrocarbon and by identifying any functional groups in the molecule that distinguish it from the parent hydrocarbon. The numbering of the parent alkane is used, as modified, if necessary, by application of the Cahn Ingold Prelog priority rules in the case that ambiguity remains after consideration of the structure of the parent hydrocarbon alone. The name of the parent hydrocarbon is modified by the application of the highest-priority functional group suffix, with the remaining functional groups indicated by numbered prefixes, appearing in the name in alphabetical order from first to last.
In many cases, lack of rigor in applying all such nomenclature rules still yields a name that is intelligible — the aim, of course, being to avoid any ambiguity in terms of what substance is being discussed.
For instance, strict application of CIP priority to the naming of the compound
NH2CH2CH2OH
would render the name as 2-aminoethanol, which is preferred. However, the name 2-hydroxyethanamine unambiguously refers to the same compound.
How the name was constructed:
1. There are two carbons in the main chain; this gives the root name "eth".
2. Since the carbons are singly-bonded, the suffix begins with "an".
3. The two functional groups are an alcohol (OH) and an amine (NH2). The alcohol has the higher atomic number, and takes priority over the amine. The suffix for an alcohol ends in "ol", so that the suffix is "anol".
4. The amine group is not on the carbon with the OH (the #1 carbon), but one carbon over (the #2 carbon); therefore we indicate its presence with the prefix "2-amino".
5. Putting together the prefix, the root and the suffix, we get "2-aminoethanol".
There is also an older naming system for organic compounds known as common nomenclature , which is often used for simple, well-known compounds, and also for complex compounds whose IUPAC names are too complex for everyday use.

Organic compounds

Aliphatic compounds
Aliphatic compounds are organic molecules that do not contain aromatic systems. ....
Hydrocarbons - Alkanes- Alkenes - Diene or Alkadienes - Alkynes - Halogenoalkanes
Aromatic compounds
Aromatic compounds are organic molecules that contain one or more aromatic ring system.
Benzene - Toluene - Styrene- Xylene- Aniline - Phenol - Acetophenone - Benzonitrile - Halogenoarenes -Naphthalene- Anthracene- Phenanthrene- Benzopyrene - Coronene- Azulene - Biphenyl
Heterocyclic compounds
Heterocyclic compounds are cyclic organic molecules whose ring(s) contain at least one heteroatom. These heteroaoms can include oxygen, nitrogen, phosphorous, and sulfur.
Pyridine - Pyrrole- Thiophene - Furan
Functional groups
Alcohols - Mercaptans - Ethers - Aldehydes- Ketones- Carboxylic acids - Esters - Carbohydrates -Alicyclic compounds - Amides- Amines - Lipids - Nitriles
Polymers
Polymers are a special kind of molecule. Generally considered "large" molecules, polymers get their reputation regarding size because they are molecules that consist of multiple smaller segments. The segments could be chemically identical, which would make such a molecule a homopolymer. Or the segments could be vary in chemical structure, which would make that molecule a heteropolymer. Polymers are a subset of "macromolecules" which is just a classification for all molecules that are considered large.
Polymers can be organic or inorganic. Commonly-encountered polymers are usually organic (e.g.,polyethylene, polypropylene, Plexiglass, etc.). But inorganic polymers (e.g., silicone) are also familiar to everyday items.

Definition of organic chemistry

Organic chemistry
Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds. Organic compounds are composed of carbon and hydrogen, and can possibly contain any of the other elements such as nitrogen, oxygen, phosphorus, and sulfur.
History
Organic chemistry as a science is generally agreed to have started in 1828 with Friedrich Woehler's synthesis of the organic, biologically significant compound urea by accidentally evaporating an aqueous solution of ammonium cyanate NH4OCN.
Characteristics of organic substances
The reason that there are so many carbon compounds is that carbon has the ability to form many carbon chains of different lengths, and rings of different sizes (catenation). Many carbon compounds are extremely sensitive to heat, and generally decompose below 300°C. They tend to be less soluble in water compared to many inorganic salts. In contrast to such salts, they tend to be much more soluble in organic solvents such as ether or alcohol. Organic compounds are covalently bonded.